Peter Martin, a long-serving American diplomat quoted by the Polish PAP news agency, said the Vatican was known for its pragmatism and habit of maintaining dialogue even under political pressure.
He suggested the current tensions would not fundamentally alter relations between Washington and the Holy See.
The remarks follow days of escalating rhetoric, with Donald Trump describing the American-born pope as "Weak on Crime” and "very liberal", and suggesting Leo's election was linked to his presidency.
US Vice-President J.D. Vance also urged the pontiff to avoid political commentary.
After Trump’s remarks, Leo said he had "no fear of the Trump administration" and would continue to speak out, having earlier condemned what he called the "madness of war".
Speaking at the White House on Thursday, Trump defended his position while addressing Leo’s criticism of the US-Israeli war with Iran.
"The Pope has to understand – it's very simple – Iran cannot have a nuclear weapon. The world would be in great danger," he said.
The US President added: "The pope can say what he wants, and I want him to say what he wants, but I can disagree. I think that Iran cannot have a nuclear weapon."
Martin noted that even during past US-Vatican disagreements, including over the Iraq war, cooperation had continued on issues such as humanitarian crises and global conflict monitoring.
Meanwhile, Pope Leo XIV, who is on an Africa tour, said in Cameroon that the world was "being ravaged by a handful of tyrants".
(ał)
Source: PAP, Reuters